Grid connection for electric discharge devices



" Aug. 9, 1932- P. c. 'GARDINNER 1, 9

GRID CONNECTION FIOR ELECTRIC DISCHARGE DEVICE Filed Jan. 27, I950 [11 Vera to)": Paul C. Gaf'cl/I17",

His fittorney. h

Patented Aug. 9, 1932 UNITED STATES PATENT; OFFECE PAUL C. GARDINER, F OAKLAND, CALIFORNIA, ASSIG-NOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK GRID CONNECTION FOR ELECTRIC DISCHARGE DEVICES Application filed January 27, 1930. Serial No. 423,617.

My invention relates to electric discharge device circuits, and has for its principal object the provision of an improved arrangement for interconnecting the grid or control electrode and the cathode of such devices.

The use of alternating current for the purpose of heating the cathode of an electric discharge device involves the dif'iculty that distortion of the signals transmitted through the device is likely to be produced bythe injection of an alternating current into the operating circuits of the device. Various arrangements, including a mid-tap connection such as that disclosed in White Patent 1,195,632 have been proposed in the past for permitting the utilization of alternating current to heat the cathode of a space discharge device. It is sometimes undesirable however to utilize a mid-tap connection, such as that disclosed by the aforesaid WVhite patent. In accordance with my invention the necessity of a mid-tap connection is avoided by the provision of an improved arrangement wherein the grid is connected to means including a winding arranged to produce a potential corresponding to that of the midpoint of the winding or other impedance device through which heating current is supplied to the cathode.

My invention will be better understood from the following description when considered in connection with the accompanying drawing, and its scope will be pointed out in the appended claim.

The drawing is a wiring diagram of a space discharge system wherein my invention has been embodied.

This system includes a space discharge de- A vice 10 which is provided with a cathode 11, a grid 12 and an anode 13. The device 10 is provided with an input circuit which includes the cathode 11, the grid 12, the secondary circuit 14- of an input transformer, a source 15 of grid bias potential, which may be 4o omitted if not required for the proper operation of the device 10, and a parallel connected circuit including a winding 16, a resistor 17 and a condenser 18. The output circuit of the device 10 includes the anode 13, the

primary 19 of an output transformer 20 and a source 21 of plate potential.

Heating current is supplied to the cathode 11 through supply terminals 22 and a transformer including a primary winding 23, a secondary winding 24, which is connected to the terminals of the cathode 11 and the tertiary winding 16 which as previously eX- plained is connected inparallel with the resistor l7 and the condenser 18. The turns of the winding 16 are preferably made about one-half the turns of the winding 24:, and the resistance 17 is made to have a value which is substantially equal to one-half the resistance of the filament 11. The condenser 18 is utilized to bypass the radio frequency currents to the left hand side of the cathode. This condenser is not necessary if a non inductive load resistance 17 is used.

With these connections the juncture 25 between the grid and anode circuits is maintained at a voltage corresponding to the voltage at the middle of the winding 24, which corresponds substantially to that at the midpoint of the cathode 11, and the effect of the alternating current component produced in the input and output circuits of the device 10 by the voltage drop of the cathode is neutralized.

WVhat I claim as new and desire to secure by Letters Patent of the United States is:

The combination of a space discharge device including a grid and a cathode provided with terminals, an alternating current transformer provided with a secondary winding connected to said terminals and with a tertiary winding connected between said cathode and grid, and a resistance of a value substantially equal to half the resistance of the oathode connected in shunt to said tertiary winding.

In witness whereof I have hereunto set my hand this 20th day of January, 1930.

PAUL C. GARDINER. 

